Putnam, Hilary (1926–2016)

2. Realism

Putnam criticized such basic elements of logical positivism as the verificationist theory of meaning, reductionism and conventionalism, while sharing the positivists’ interest in and respect for natural science (see Logical positivism §2). He maintained that realism is the only philosophy that does not render the success of science a miracle (see Realism and antirealism; Scientific realism and antirealism §3). His argument from success is presented as structurally similar to hypothetico-deductive arguments within science: realism provides the best explanation for the success of science in the same way atoms and genes provide explanations for observable phenomena. However, this analogy is problematic in that it is purely formal. Realism has no empirical import beyond that of its alternatives, a desideratum scientific hypotheses must meet.

Putnam’s criticism of conventionalism is developed in An Examination of Grünbaum’s Philosophy of Geometry and The Refutation of Conventionalism. On the Reichenbach–Grünbaum conception, the core of the transition from Newtonian to relativistic mechanics is a new definition of the spacetime metric. The definition chosen is a matter of convenience, not of truth (see Conventionalism §1). According to Putnam, however, meaning change is only part of the story; theoretical concepts have explanatory import, and must be anchored in a theory that meets both empirical and non-empirical constraints. There is, therefore, much less freedom than the conventionalist alleges. Putnam raises a similar objection to Quine’s celebrated indeterminacy of translation thesis (see Quine, W.V. §9). Here, as in the case of conventionalism, underdetermination is an illusion created by considering an unreasonably limited set of constraints. Once we recognize coherence, simplicity, and so on, as constraints on translation or theory-construction, conventionality and indeterminacy vanish.